Functionalization of hexakis methanofullerene malonate crown-ethers: promising octahedral building blocks for molecular networks

Pierrat, Philippe; Vanderheiden, Sylvia; Müller, Thierry; Bräse, Stefan

doi:10.1039/b900367c

Cited by 65 publications

(34 citation statements)

References 56 publications

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“…Apart from their unique architecture, hexakis adducts derived from the functionalization of the six e double bonds of C 60 are very attractive structures in the synthesis of functional fullerene materials. [45][46][47][48][49][50] The results of the present study lead to the conclusion that the [4+2] cycloaddition of orthoquinodimethanes with the C 60 is a kinetically controlled reaction. The in situ thermal generation of ortho-quinodimethanes from the corresponding 1,2-bis(bromomethyl)benzene precursors requires high temperatures (110 o C) and is followed by the fast, irreversible [4+2] cycloaddition reaction with C 60 to afford thermally stable products.…”

Section: Scheme 6 Synthesis Of Macrocyclic Tether 21mentioning

confidence: 63%

A study towards the regioselective synthesis of the e,e,e trisadduct of C60 via the [4+2] Diels-Alder reaction with tethers bearing ortho-quinodimethane precursors

Ioannou¹,

Chronakis²

2015

Arkivoc

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The regioselective synthesis of an e,e,e trisadduct of C 60 via the Diels-Alder reaction with orthoquinodimethanes has been attempted employing the tether-directed remote functionalization approach. Opened-structure tether 10 and macrocyclic tethers 16 and 21 were synthesized for this purpose. The functionalization of C 60 afforded inseparable mixtures of regiomeric trisadducts and the regioselective formation of the e,e,e trisadduct was not feasible even when the more preorganized tethers 16 and 21 were employed. The in situ thermal generation of orthoquinodimethanes from the 1,2-bis(bromomethyl)benzene precursors requires high temperatures and is followed by fast, irreversible cycloaddition with C 60 to afford thermally stable products, which prevents the achievement of high regioselectivities.

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Section: Scheme 6 Synthesis Of Macrocyclic Tether 21mentioning

confidence: 63%

A study towards the regioselective synthesis of the e,e,e trisadduct of C60 via the [4+2] Diels-Alder reaction with tethers bearing ortho-quinodimethane precursors

Ioannou¹,

Chronakis²

2015

Arkivoc

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“…The enantiomeric excess was determined by HPLC or GC on chiral stationary phases. General procedure for the sixfold Heck reaction on a fullerene derivative 293 [392]: A mixture of NaHCO 3 (15.0 equiv. ), NBu 4 HSO 4 (6.00 equiv.…”

Section: )mentioning

confidence: 99%

“…Ph Even the extension to a fullerene with six iodophenyl-containing annelated cyclopropanedicarboxylate crown ether-ester units as in 293 is possible, as exemplified by the successful sixfold Heck reaction to give 294 in 94% yield (Scheme 8.62) [392]. Double, triple, and even quadruple Heck-Diels-Alder cascade reactions involving 1,4-diiodo-, 1,3,5-triiodo-, or 1,2,4,5-tetraiodobenzene, respectively, and bicyclopropylidene (16) have been accomplished (cf.…”

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confidence: 99%

Cross‐Coupling of Organyl Halides with Alkenes – The Heck Reaction

Bräse¹,

Meijere²

2013

Metal‐Catalyzed Cross‐Coupling Reactions and More

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The carbopalladation of an alkene by an organylpalladium halide is the essential step in one of the major contemporary metal-catalyzed C-C coupling reactions. About 45 years ago, a Japanese and an American group almost simultaneously designed and executed palladium-mediated coupling reactions of aryl and alkenyl halides with alkenes [1]. In subsequent investigations, Richard Heck and his group developed this reaction into a catalytic transformation and started to demonstrate its usefulness as well as its rather broad scope. The real push to utilize this powerful C-C-bondforming process, however, started only around the mid-1980s, and by now, an impressive number of publications have established the meanwhile so-called Heck reaction [2] 1) as an indispensable method in Organic Synthesis [3][4][5][6][7]. The universal recognition of the importance of the Heck reaction and the Negishi as well as the Suzuki coupling eventually won the Nobel Prize for Richard Heck along with Ei-ichi Negishi and Akira Suzuki in 2010. The applications of the Heck reaction range from the preparation of -functionalized and unfunctionalized -hydrocarbons, novel polymers, and dyes to new advanced enantioselective syntheses of natural products and biologically active nonnatural compounds. The more or less simultaneous developments of mechanistically related variants, namely, the Kumada, Suzuki, Stille, Hiyama, and Negishi coupling reactions (Chapters 12, 2, 3, 4, and 15, respectively) of metallated alkenes and arenes with aryl and alkenyl halides or the metal-catalyzed formation and cycloisomerization of enynes have drawn profit from the improvement of and mechanistic insights into the Heck reaction. This, of course, applies vice versa as well. Using only a catalytic amount of a palladium(0) complex or a precursor to a palladium species, the Heck reaction can bring about unprecedented structural changes, particularly when conducted intramolecularly. The full potential of this palladium-catalyzed process is still being further explored as demonstrated by a total of over 7000 publications in the past 40 years by 1) The alkynylation of aryl and alkenyl halides, frequently also considered as Heck reactions, is described in Chapter 6.

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“…In order to overcome this problem, we have recently developed an efficient threestep synthesis of a simple C 60 hexakisadduct derivative bearing 12 azide groups [3] and shown that the copper-mediated Huisgen 1,3-dipolar cycloaddition [4] of azides and alkynes resulting in 1,2,3-triazoles, one of the most powerful click reactions to date, [5] is an ideal tool to efficiently produce functionalized hexasubstituted fullerenes. [3,6,7] In this paper, we now report on the preparation of a C 60 hexakisadduct bearing 12 trimethylsilyl (TMS)-protected alkyne groups allowing the attachment of 12 azide units under the copper-mediated Huisgen 1,3-dipolar cycloaddition conditions. Moreover, by combining these two complementary approaches, we also show that functionalized mixed hexaadducts of C 60 can easily be prepared.…”

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confidence: 99%

A Click–Click Approach for the Preparation of Functionalized [5:1]‐Hexaadducts of C₆₀

Iehl

Nierengarten

2009

Chemistry A European J

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Fullerene hexakisadducts with a T h -symmetrical octahedral addition pattern are unique three-dimensional molecules with a spherical framework.[1] Whereas such compounds can be prepared in good yields from relatively simple malonates, [2] structurally more complicated systems are generally obtained in rather low yields and/or HPLC is often required for their purification. In order to overcome this problem, we have recently developed an efficient threestep synthesis of a simple C 60 hexakisadduct derivative bearing 12 azide groups [3] and shown that the copper-mediated Huisgen 1,3-dipolar cycloaddition [4] of azides and alkynes resulting in 1,2,3-triazoles, one of the most powerful click reactions to date, [5] is an ideal tool to efficiently produce functionalized hexasubstituted fullerenes. [3,6,7] In this paper, we now report on the preparation of a C 60 hexakisadduct bearing 12 trimethylsilyl (TMS)-protected alkyne groups allowing the attachment of 12 azide units under the copper-mediated Huisgen 1,3-dipolar cycloaddition conditions. Moreover, by combining these two complementary approaches, we also show that functionalized mixed hexaadducts of C 60 can easily be prepared. To this end, we have prepared a C 60 hexaadduct bearing ten azides and two TMS-protected alkyne groups allowing the successive attachment of ten alkyne building blocks and two azide units via successive click reactions. As click reactions are modular, tolerant to a wide range of functional groups, and high yielding, a large number of functionalized [5:1]-hexaadducts of C 60 should become easily accessible by using this new synthetic approach.The preparation of the C 60 hexakisadduct bearing 12 trimethylsilyl (TMS)-protected alkyne groups is depicted in Scheme 1. Reaction of malonyl dichloride with alcohol 1 in the presence of pyridine afforded malonate 2 in 62 % yield. Hexakisadduct 3 was then readily synthesized by the reaction of C 60 (1 equiv) with 2 (10 equiv), CBr 4 (100 equiv) and 1,8-diazabicycloA C H T U N G T R E N N U N G [5.4.0]undec-7-ene (DBU, 20 equiv) in o-dichlorobenzene (ODCB) at room temperature. Compound 3 was thus obtained in 49 % yield. The chemical structure of compound 3 was easily confirmed by 1 H and 13 C NMR analysis. In particular, the 13 C NMR spectrum of fullerene hexakisadduct 3 is in full agreement with its T h -symmetrical structure and shows the three expected fullerene resonances

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Functionalization of hexakis methanofullerene malonate crown-ethers: promising octahedral building blocks for molecular networks

Abstract: Hexaazido and hexaiodo macrocyclic methanofullerenes undergo high-yielding sixfold click reactions or sixfold Heck, Sonogashira and Suzuki cross-coupling reactions, respectively, to yield all organic building blocks for higher molecular architectures.

Cited by 65 publications

References 56 publications

A study towards the regioselective synthesis of the e,e,e trisadduct of C60 via the [4+2] Diels-Alder reaction with tethers bearing ortho-quinodimethane precursors

A study towards the regioselective synthesis of the e,e,e trisadduct of C60 via the [4+2] Diels-Alder reaction with tethers bearing ortho-quinodimethane precursors

Cross‐Coupling of Organyl Halides with Alkenes – The Heck Reaction

A Click–Click Approach for the Preparation of Functionalized [5:1]‐Hexaadducts of C₆₀

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Functionalization of hexakis methanofullerene malonate crown-ethers: promising octahedral building blocks for molecular networks

Abstract: Hexaazido and hexaiodo macrocyclic methanofullerenes undergo high-yielding sixfold click reactions or sixfold Heck, Sonogashira and Suzuki cross-coupling reactions, respectively, to yield all organic building blocks for higher molecular architectures.

Cited by 65 publications

References 56 publications

A study towards the regioselective synthesis of the e,e,e trisadduct of C60 via the [4+2] Diels-Alder reaction with tethers bearing ortho-quinodimethane precursors

A study towards the regioselective synthesis of the e,e,e trisadduct of C60 via the [4+2] Diels-Alder reaction with tethers bearing ortho-quinodimethane precursors

Cross‐Coupling of Organyl Halides with Alkenes – The Heck Reaction

A Click–Click Approach for the Preparation of Functionalized [5:1]‐Hexaadducts of C60

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A Click–Click Approach for the Preparation of Functionalized [5:1]‐Hexaadducts of C₆₀